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Horn Rail (1988)

The J-29 Horn Rail (警笛レール) was released in 1988 and represents an iron bridge that a train must sound its horn when crossing. Switches under the rails trigger a shrill "horn" when a train rolls over it. The Horn Rail was originally produced in Japan with production moving to Thailand in the 90s before the horn rail's eventual discontinuation in 1998. Although it does not need to be used as a bridge, the Horn Rail includes the side pieces of the Iron Bridge as well as two Bridge Girders to create an elevated bridge.

The base of the Horn Rail is the length of a standard straight rail and includes a battery compartment for two AA batteries, a power switch, an enclosure for the piezo-electric beeper inside, and contact patches in the rail surface that press on switches inside when a train passes to turn on the horn sound. The battery compartment includes a stud pattern to attach the sign to and moldings along the side of the tracks allow for the sides of an Iron Bridge to be inserted inside without the need for Block Bridge Girders.

The sign, which uses the LEGO-compatible three stud by three stud sign mold, reads "警笛" or simply "horn." My example is a later made in Thailand release, so the sign and base molding are both updated with Thailand marks over where they originally said Japan.

Inside the bridge is the power switch, train detection switches, and the circuit board that produces the horn. The positive lead from the battery terminal goes through the power switch to a common positive plate that sits under the tracks supported by nodules in the molding of the bottom blue plate. The blue portion of the rail pushes down on a set of contacts that, when pressed down against the static contacts, complete the circuit and allow the buzzer to go off. The rail assemble essentially acts as two switches in parallel, and a train (or anything else) that presses down on the blue rails will set off the horn.

The circuit board contains a small pieze-electric beeper to produce the horn, a Toshiba 74HC00AP quad NAND gate integrated circuit to drive it, and some support circuitry.

Click for video with sound

The horn that the Horn Rail produces is rather shrill and does not particularly sound that much like a train horn to me. When actually running, it seems that there is some "bounce" in the switches, particularly when new cars enter the area of track that senses trains passing. When simply held down, the noise is rather annoying.